E2X.T8-aux-high on a Worcester Bosch Greenstore LECP ground source heat pump: Electric additional heat shut down due to high temperature E2X.T8
Short answer
On a Worcester Bosch heat pump, E2X.T8-aux-high means: Electric additional heat shut down due to high temperature E2X.T8. The heat pump keeps running with some functions stopped. An engineer is needed to fix the cause.
Reviewed 23 September 2026 · 1 source
What it means
The manual says: Electric additional heat shut down due to high temperature E2X.T8.
Part involved: T8 (>80 C).
When it shows: T8 exceeds 80 C in additional heat mode; heater off until below 76 C.
Likely causes:
- T8 exceeds 80 C in additional heat mode; heater off until below 76 C.
Is it safe?
| Does the heat pump stop? | Partly |
|---|---|
| Severity | Warning |
| Engineer needed? | Yes |
The heat pump keeps running with some functions stopped.
Resetting itself: yes.
Manual reset: Automatic.
What you can check
- Read and note the full alarm text and category letter shown on the controller and pass it to your installer.
What the engineer will check
- Diagnose per chapter 21: T8 exceeds 80 C in additional heat mode; heater off until below 76 C.
Who to ask for: heat pump installer / heating engineer.
Certification: None specific for hydraulic checks; MCS-certified installer recommended for system changes.
What you might notice
Sources
- Installation, Commissioning and Servicing Instructions Worcester Greenstore LECP GSHP (System/Combi 6-11 kW) ↗ · 6 720 806 768 (2013/02) · page 62 · Reviewed 23 September 2026
A code explains what the controller detected, not a confirmed root cause.
Reviewed: 23 September 2026